Isobutyryl-CoA dehydrogenase deficiency


Isobutyryl-coenzyme A dehydrogenase deficiency, commonly known as IBD deficiency, is a rare metabolic disorder in which the body is unable to process certain amino acids properly. People with this disorder have inadequate levels of an enzyme that helps break down the amino acid valine, resulting in a build up of valine in the urine, a symptom called valinuria.


Babies with this disorder are usually healthy at birth. The signs and symptoms may not appear until later in infancy or childhood and can include poor feeding and growth (failure to thrive), a weakened and enlarged heart (dilated cardiomyopathy), seizures, and low numbers of red blood cells (anemia). Another feature of this disorder may be very low blood levels of carnitine (a natural substance that helps convert certain foods into energy). Isobutyryl-CoA dehydrogenase deficiency may be worsened by long periods without food (fasting) or infections that increase the body's demand for energy. Some individuals with gene mutations that can cause isobutyryl-CoA dehydrogenase deficiency may never experience any signs and symptoms of the disorder.


The proper treatment of IBDH deficiency is not yet established, because of the wide variation in clinical phenotype and lack of long-term follow-up. Asymptomatic patients may not require specific treatment, whereas those patients who are symptomatic and have low plasma carnitine may benefit from carnitine supplementation. Because the diagnosis of IBDH deficiency is complex, the pediatrician is advised to manage the patient in close collaboration with a consulting pediatric metabolic disease specialist. It is recommended that parents travel with a letter of treatment guidelines from the patient’s physician.